1. Field of the Invention
The present invention relates to a liquid crystal display device for a head-up display device, and a head-up display device, and more particularly to a head-up display device using a liquid crystal display device.
2. Description of the Related Art
There is known a head-up display (HUD) device which projects display light from a liquid crystal display device onto a windshield of a vehicle, for example, and displays a virtual image (display image). In this head-up display device, for example, illumination light from a backlight passes through a liquid crystal display device as display light, and the display light is reflected by a reflecting mirror (or a concave mirror). By projecting the reflected light onto a display member such as a windshield or a combiner, a driver visually recognizes a virtual image which is displayed on the display member. Thereby, the driver can read information, without substantially moving the view field from the driving state.
In the head-up display device, because of the configuration thereof, there is a case in which part of light (outside light) such as sunlight from the outside (in particular, a light component which is parallel and opposite to the optical path of the backlight) is radiated on the liquid crystal display device which is used for the head-up display device. In this case, an unnecessary image, which is not to be displayed, appears on the windshield, due to the outside light reflected on the display surface of the liquid crystal display device. Thereby, the display characteristics of the liquid crystal display device deteriorate.
In addition, if the intensity (luminance) of light, which passes through the liquid crystal display device, is low, a virtual image, which is projected on the windshield, becomes dark, and the unnecessary image due to the outside light becomes more conspicuous. As a result, the display characteristics of the liquid crystal display device deteriorate.